如何选择具有max（选择字段）和另一（特定字段）的一行？

Question

How to select one row with max(select field) and another (specific field)?

Below is my code
1. Get to know max(select field) first
2. Then select all field within the row. but step 2 doesn't return any thing, wonder know why?
And is there shorter syntax for same result??
Thanks.

$gid = 1;

// get lid
$sth = $db->prepare("SELECT MAX(lid) as lid FROM t WHERE gid = :gid");
$sth->bindParam(':gid', $gid);
$sth->execute();
$arr = $sth->fetch(PDO::FETCH_ASSOC);
print $arr['lid'];

// nothing return??
$lid = $arr['lid'];
$sth = $db->prepare("SELECT * FROM t WHERE gid = :gid AND lid = :lid");
$sth->bindParam(':gid', $gid);
$sth->bindParam(':lid', $lid);
$row = $sth->fetch();
print_r($row);

Answer 1

You could do it in one step with this query:

$sql = "SELECT t.* 
        FROM t 
        INNER JOIN (
            SELECT MAX(lid) as lid 
            FROM t 
            WHERE gid = :gid
        ) AS x ON t.lid = x.lid";
$sth = $db->prepare($sql);
$sth->bindParam(':gid', $gid);
$sth->execute();
$arr = $sth->fetch(PDO::FETCH_ASSOC);
print_r($arr);